Radiation therapy is a non-invasive medical treatment involving radiating one or more portions of a patient, such as neoplastic tissue, with high doses of radiation at one or more extremely precise locations. The radiation is delivered to focus high doses within the target tissue while attempting to minimize dose to surrounding normal tissues. Radiation therapy includes radiosurgery, including stereotaxic radiosurgery (SRS), that provides a form of non-invasive surgery that allows doctors to treat medical conditions. Examples of such conditions include malignant lesions, intracranial tumors, and various forms of cancers. In radiosurgery, neoplastic tissue such as a lesion or tumor existing in a patient's body is exposed to (i.e., irradiated with) focused radiation, such as collimated gamma radiation, delivered from a radiating device. Typically, the radiating device applies doses of radiation at prescribed strengths to a target area in order to inhibit the growth of the tissue in that area by altering the molecular structure of cells that form the tissue.
Included in radiation therapy, is a technology referred to as intensity modulated radiation therapy (IMRT). IMRT itself includes the use of proton radiation (intensity modulated proton therapy, or IMPT) and other particulate radiation. Typically, IMRT involves the use of a special multi-leaf collimator and high power computers to customize dose distributions to the specification of not only minimal dose volume relationships in targets but also maximal dose volume relationships required to spare surrounding normal tissues and organs from adverse effects. Part of this technology, known as inverse planning, involves the radiation oncologist entering a comprehensive prescription into a workstation with parallel processing computers to calculate, or optimize, the radiation intensity distributions needed to fulfill the prescription.
Several different persons are involved in providing radiation therapy to patients, including an oncologist, a physicist, and a therapist. The radiation oncologist, or dosimetrist, is a physician whose job it is to determine treatment for patients. The oncologist is certified and authorized to approve radiation therapy plans. To develop a radiation plan, the oncologist uses information regarding the patient and works with a qualified medical physicist to determine the therapy to apply to a patient. The oncologist uses the desired therapy in conjunction with computerized determinations of what radiation distributions that a radiating device can provide to determine a dosimetry/radiation plan for the patient to treat the target areas while limiting radiation to healthy tissue. The qualified medical physicist is someone familiar with therapeutic radiological physics, a.k.a. radiation oncology physics, and helps the oncologist appreciate with radiation therapies (e.g., radiation distributions) are available. The physicist is also responsible for calibrating the radiating device and performing quality assurance to help ensure that patients are being treated as intended. The physicist further works with the radiation therapist to plan the actual application of radiation to the patient. The radiation therapist, or operator, is the person that is licensed to use a radiating device on a patient and is responsible for implementing the radiation plan developed by the physicist and oncologist.